:root {
  --bg: #0c0d10;
  --panel: #15171c;
  --panel-2: #1c1f26;
  --line: #282c35;
  --ink: #e9eaee;
  --ink-dim: #9aa0ac;
  /* Clears WCAG AA (4.5:1) on all three backgrounds at 12–14px, which the
     older #6e7480 did not — it read as grey mud on a classroom projector. */
  --ink-faint: #8a90a0;
  --accent: #e2732b;
  --accent-soft: rgba(226, 115, 43, 0.14);
  --zh: #7fb7c9;
  --radius: 14px;
  --pad: 22px;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.65 -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans TC",
        "PingFang TC", "Helvetica Neue", Arial, sans-serif;
  padding-bottom: 90px;
}

body.big { font-size: 19px; }

.wrap {
  max-width: 780px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ---------- masthead ---------- */

.masthead {
  padding: 54px 0 34px;
  background:
    radial-gradient(120% 90% at 12% 0%, rgba(226, 115, 43, 0.16), transparent 62%),
    linear-gradient(#101216, var(--bg));
  border-bottom: 1px solid var(--line);
}

.kicker {
  margin: 0 0 10px;
  font-size: 12px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
}

.masthead h1 {
  margin: 0;
  font-size: clamp(38px, 9vw, 60px);
  line-height: 1;
  letter-spacing: -0.03em;
  font-weight: 800;
}

.sub {
  margin: 14px 0 0;
  color: var(--ink-dim);
  max-width: 48ch;
}

.zh-inline { color: var(--zh); }

/* ---------- song tabs ---------- */

.songbar {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(12, 13, 16, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}

.tabs {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding: 12px 0;
  scrollbar-width: none;
}

.tabs::-webkit-scrollbar { display: none; }

.tab {
  flex: 0 0 auto;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ink-dim);
  border-radius: 999px;
  padding: 9px 15px;
  font: inherit;
  font-size: 14px;
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}

.tab:hover { color: var(--ink); border-color: #3a3f4b; }

.tab[aria-selected="true"] {
  background: var(--accent-soft);
  border-color: var(--accent);
  color: var(--ink);
}

.tab .yr {
  color: var(--ink-faint);
  margin-left: 7px;
  font-variant-numeric: tabular-nums;
}

.tab[aria-selected="true"] .yr { color: var(--accent); }

/* ---------- panels ---------- */

.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: var(--pad);
  margin: 20px 0;
}

.panel-h {
  margin: 0 0 4px;
  font-size: 13px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 700;
}

.panel-h-zh {
  color: var(--ink-faint);
  letter-spacing: 0.06em;
  text-transform: none;
  font-weight: 500;
  margin-left: 6px;
}

.hint {
  margin: 0 0 16px;
  color: var(--ink-faint);
  font-size: 14px;
  max-width: 62ch;
}

.song-head h2 {
  margin: 0;
  font-size: clamp(26px, 6vw, 34px);
  line-height: 1.15;
  letter-spacing: -0.02em;
}

.meta {
  margin: 8px 0 14px;
  color: var(--ink-faint);
  font-size: 14px;
}

.meta .dot { margin: 0 8px; opacity: 0.5; }

.yt {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 0 0 18px;
  padding: 8px 14px;
  border: 1px solid var(--line);
  border-radius: 9px;
  color: var(--ink-dim);
  text-decoration: none;
  font-size: 14px;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}

.yt:hover,
.yt:focus-visible {
  background: rgba(255, 77, 77, 0.12);
  border-color: #ff4d4d;
  color: var(--ink);
}

.yt[hidden] { display: none; }

.yt .play { color: #ff4d4d; font-size: 12px; }

.yt .ext { color: var(--ink-faint); font-size: 12px; }

.about { margin: 0 0 14px; }

/* ---------- Chinese reveal ---------- */

.zh-chip {
  border: 1px solid var(--line);
  background: transparent;
  color: var(--zh);
  border-radius: 8px;
  width: 30px;
  height: 26px;
  font: inherit;
  font-size: 13px;
  line-height: 1;
  cursor: pointer;
  flex: 0 0 auto;
  transition: background 0.15s, border-color 0.15s;
}

.zh-chip:hover { background: rgba(127, 183, 201, 0.12); border-color: var(--zh); }

.zh-chip[aria-expanded="true"] {
  background: rgba(127, 183, 201, 0.16);
  border-color: var(--zh);
}

.zh-text {
  color: var(--zh);
  margin: 12px 0 0;
  padding-left: 12px;
  border-left: 2px solid rgba(127, 183, 201, 0.4);
  line-height: 1.8;
}

.zh-text[hidden] { display: none; }

/* ---------- vocabulary ---------- */

.vocab {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.vocab li {
  background: var(--panel-2);
  border: 1px solid var(--line);
  border-radius: 11px;
  padding: 14px 16px;
}

.v-top {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.v-word {
  font-weight: 700;
  font-size: 17px;
  letter-spacing: -0.01em;
}

.v-pos {
  color: var(--ink-faint);
  font-size: 13px;
  font-style: italic;
}

.v-gloss { margin: 6px 0 0; color: var(--ink-dim); }

.v-ex {
  margin: 9px 0 0;
  padding-left: 12px;
  border-left: 2px solid var(--line);
  color: var(--ink);
  font-size: 15px;
}

.v-ex b { color: var(--accent); font-weight: 600; }

.v-zh {
  margin: 9px 0 0;
  color: var(--zh);
  font-size: 15px;
}

.v-zh[hidden] { display: none; }

/* ---------- language focus ---------- */

.focus h4 {
  margin: 0 0 8px;
  font-size: 18px;
  letter-spacing: -0.01em;
}

.focus p { margin: 0 0 12px; color: var(--ink-dim); }

.focus em { color: var(--ink); font-style: italic; }

.focus strong { color: var(--accent); font-weight: 600; }

.focus s { color: var(--ink-faint); }

.focus ul {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 8px;
}

.focus ul li {
  background: var(--panel-2);
  border-radius: 9px;
  padding: 11px 14px;
  border: 1px solid var(--line);
}

/* ---------- lyrics workspace ---------- */

.lyrics-input {
  width: 100%;
  background: var(--panel-2);
  border: 1px solid var(--line);
  border-radius: 11px;
  color: var(--ink);
  font: inherit;
  padding: 13px 15px;
  resize: vertical;
  line-height: 1.7;
}

.lyrics-input:focus {
  outline: none;
  border-color: var(--accent);
}

.lyrics-input::placeholder { color: var(--ink-faint); }

.row {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 12px;
  flex-wrap: wrap;
}

.btn {
  border: 1px solid var(--accent);
  background: var(--accent-soft);
  color: var(--ink);
  border-radius: 9px;
  padding: 9px 16px;
  font: inherit;
  font-size: 15px;
  cursor: pointer;
  transition: background 0.15s;
}

.btn:hover { background: rgba(226, 115, 43, 0.24); }

.btn.ghost {
  border-color: var(--line);
  background: transparent;
  color: var(--ink-dim);
}

.btn.ghost:hover { background: var(--panel-2); color: var(--ink); }

.btn.small { padding: 7px 12px; font-size: 14px; }

.count { color: var(--ink-faint); font-size: 14px; }

.lyrics-out { margin-top: 18px; }

.lyrics-out:empty { margin-top: 0; }

.lline {
  display: flex;
  gap: 12px;
  padding: 7px 0;
  border-bottom: 1px solid rgba(40, 44, 53, 0.6);
  line-height: 1.7;
}

.lline:last-child { border-bottom: 0; }

.lline.blank { padding: 6px 0; border-bottom: 0; }

.lnum {
  flex: 0 0 26px;
  text-align: right;
  color: var(--ink-faint);
  font-size: 13px;
  font-variant-numeric: tabular-nums;
  padding-top: 3px;
  user-select: none;
}

.ltext { flex: 1; }

.hit {
  background: var(--accent-soft);
  border-bottom: 1px solid var(--accent);
  border-radius: 3px;
  padding: 1px 3px;
  cursor: pointer;
  color: var(--ink);
}

.hit:hover { background: rgba(226, 115, 43, 0.3); }

.hit-pop {
  display: block;
  margin: 6px 0 4px 0;
  padding: 10px 13px;
  background: var(--panel-2);
  border: 1px solid var(--accent);
  border-radius: 9px;
  font-size: 15px;
  color: var(--ink-dim);
}

.hit-pop b { color: var(--ink); }

.hit-pop .zh { color: var(--zh); }

/* ---------- questions ---------- */

.questions {
  margin: 0;
  padding-left: 22px;
  display: grid;
  gap: 12px;
}

.questions li { padding-left: 4px; }

.questions li::marker { color: var(--accent); font-weight: 700; }

/* ---------- footer ---------- */

.foot {
  color: var(--ink-faint);
  font-size: 13px;
  padding-top: 8px;
  padding-bottom: 30px;
}

.foot p { margin: 0; }

/* ---------- teacher panel ---------- */

.teacher-toggle {
  position: fixed;
  right: 18px;
  bottom: 18px;
  z-index: 40;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ink-faint);
  font-size: 17px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
}

.teacher-toggle:hover { color: var(--ink); border-color: var(--accent); }

.teacher-toggle[aria-expanded="true"] {
  color: var(--accent);
  border-color: var(--accent);
}

.teacher {
  position: fixed;
  right: 18px;
  bottom: 74px;
  z-index: 40;
  width: 268px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px 18px;
  box-shadow: 0 18px 44px rgba(0, 0, 0, 0.55);
}

.teacher[hidden] { display: none; }

.teacher h4 {
  margin: 0 0 12px;
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

.switch {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 7px 0;
  cursor: pointer;
  font-size: 15px;
}

.switch input { accent-color: var(--accent); width: 16px; height: 16px; }

.tiny { color: var(--ink-faint); font-size: 12px; }

.teacher .btn { margin-top: 10px; width: 100%; }

.note { margin: 12px 0 0; line-height: 1.5; }

@media (max-width: 480px) {
  .panel { padding: 18px 16px; }
  .teacher { left: 18px; width: auto; }
}